ASoC: simple-card: set cpu dai clk in hw_params

The simple-card driver currently accepts a clock node in the cpu dai
sub-node and only uses it as an alternative to the
'system-clock-frequency' property to get the current frequency.

This patch adds another use of the passed clock node. If mclk-fs is
specified, the clocks in cpu and codec dai sub-nodes will be set to
the calculated rate (stream rate * mclk_fs) in hw_params.

This allows platforms to pass tuneable clocks as phandle that will
automatically be set to the right rates.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/simple-card.txt

@@ -86,6 +86,11 @@ Optional CPU/CODEC subnodes properties:
 					  in dai startup() and disabled with
 					  clk_disable_unprepare() in dai
 					  shutdown().
+					  If a clock is specified and a
+					  multiplication factor is given with
+					  mclk-fs, the clock will be set to the
+					  calculated mclk frequency when the
+					  stream starts.
 - system-clock-direction-out		: specifies clock direction as 'out' on
 					  initialization. It is useful for some aCPUs with
 					  fixed clocks.

sound/soc/generic/simple-card.c

@@ -135,6 +135,18 @@ static void asoc_simple_card_shutdown(struct snd_pcm_substream *substream)
 	asoc_simple_card_clk_disable(&dai_props->codec_dai);
 }
 
+static int asoc_simple_set_clk_rate(struct asoc_simple_dai *simple_dai,
+				    unsigned long rate)
+{
+	if (!simple_dai->clk)
+		return 0;
+
+	if (clk_get_rate(simple_dai->clk) == rate)
+		return 0;
+
+	return clk_set_rate(simple_dai->clk, rate);
+}
+
 static int asoc_simple_card_hw_params(struct snd_pcm_substream *substream,
 				      struct snd_pcm_hw_params *params)
 {
@@ -154,6 +166,15 @@ static int asoc_simple_card_hw_params(struct snd_pcm_substream *substream,
 
 	if (mclk_fs) {
 		mclk = params_rate(params) * mclk_fs;
+
+		ret = asoc_simple_set_clk_rate(&dai_props->codec_dai, mclk);
+		if (ret < 0)
+			return ret;
+
+		ret = asoc_simple_set_clk_rate(&dai_props->cpu_dai, mclk);
+		if (ret < 0)
+			return ret;
+
 		ret = snd_soc_dai_set_sysclk(codec_dai, 0, mclk,
 					     SND_SOC_CLOCK_IN);
 		if (ret && ret != -ENOTSUPP)